It wasn't all that long ago when owning a car was a
real hands-on experience.

Carburetors, points and
condensers, spark plugs that only lasted a few thousand
miles, single-weight oil and take-it-or-leave-it quality meant
that like it or not, you were involved with your
machine.

Cars have evolved (some would say devolved) to the
point where many owners never even open the hood and
have no idea what an engine looks like.
Motorcycles are somewhere in between.

Motorcycle ownership requires a certain
amount of commitment to understanding when and how
everything is working correctly. It's more than a
curiosity -- it's a matter of
life and death, because ignoring a mechanical problem on
a motorcycle can be, at a minimum, very dangerous. If you don't
understand why, then you probably shouldn't be riding in
the first place!

Nevertheless, many owners have a very limited
knowledge of their bike and depend on their local dealer
to do everything from an oil change to a saddlebag
installation. I can certainly understand this if
it's a matter of time and scheduling, although surely it
would take way longer to make an appointment, bring the
bike in, get a ride home and back and then pick the bike
up than it would for the owner to spend the half-hour or
so it takes to change his or her own oil.

I can
also understand how some owners just aren't as
fascinated by combustion engines and the mechanics of
riding a motorcycle as I am. But motorcycle
ownership is all about an intimate
experience of rider and machine, which means that it's important to know
what's happening with every nut and bolt on the bike.
Owner-performed regular maintenance tasks like an oil
change are a very good way to get down-and-dirty with
the machine to keep tabs on its condition.

You'd be surprised at how much you can learn about
a motorcycle when you're up to your
elbows in its dirty details. I've found everything
from critical bits and pieces that needed replacement to
important nuts and bolts that have vibrated loose.
Obviously, it's much better to find out about this in the garage
than when you're leaned over in a 60MPH sweeper.

Which brings us to the topic of removing a plastic
motorcycle gas tank. Lurking on several motorcycle
user group email lists has indicated to me that too many
owners, for one reason or another, have never attempted
to remove the gas tank on their bike to inspect or
change the spark plugs, air filter, inspect the wiring
or to perform other important maintenance or repair
tasks.

The prevalence of fairings and plastic on many bikes
means that removing a gas tank is sometimes more complex
than it should be, and perhaps this puts some owners off. Removing all that stuff can
sometimes add
a half-hour or more to even the most basic maintenance
task, which is maybe why some owners have
given up on doing it themselves. But with
perseverance and patience, it can be done.

I recently had to remove the plastic gas tank on our 1998
Triumph Tiger to take a look at the carburetors
(another interesting project that I'll be reporting on
soon), so I figured I may as well take some photos and
write it up. Now you experienced mechanical types might
think that this is a too-basic maintenance task for a
feature article, but my feeling is that you just never
know who might benefit by this information.

Maybe some motorcycle owners would like to do some of
their own work and they only need a little bit of
guidance to give them the confidence and show them that
it can be done.

So what's so special about removing a plastic
motorcycle gas tank? In the case of the Tiger, the
fairing side panels are fastened to the bike via some
threaded inserts that are embedded flush
into the walls of the plastic tank itself.

I'm not
sure how common this is but there are some extra
cautions that must be taken when removing and replacing
the panels if they're attached to a plastic gas tank.
The Tiger uses specially designed Allen head cap screws
(photo below) to attach the side panels to the gas tank
and the rest of the bike.

This special cap screw is commonly used to attach
motorcycle fairing panels. It has a machined
shoulder that acts as a stop so it can't be screwed in
too far. The shoulder is deep enough to allow room
for the thickness of the panel (seen in the photo below)
and also to prevent over-tightening, which
might pull the threaded insert right out of the plastic
tank.

The rubber washer keeps the head of the cap screw
from damaging the plastic side panel but also provides a
bit of resistance to the screw after it's inserted,
similar to the action of a split lock washer. The
outward pressure of the washer helps to keep the threads
tight and prevents the screw from backing out of the
threaded insert.

What this all means is that it's important to make
sure the cap screws aren't over tightened and that the
panel and holes are lined up as close as possible to
ensure that everything fits with the least amount of
stress and strain. Read your owner's manual and/or
shop manual for the correct torque settings for these
screws and don't guess!

Once all the side panel cap screws are removed, the
front and rear gas tank bolts must also be removed.
These are typically found on most motorcycle gas tanks, which
usually have either one or two bolts in the rear of the
tank that hold it on to the motorcycle frame and one or
two in the front of the tank. On the Tiger, the
rear bolts have steel and rubber washers, as seen in
this photo:

The front of the Tiger's gas tank is secured with a single 9mm bolt
with a wide steel and rubber washer. This bolt
really doesn't hold the tank down on to the frame per
se; it
simply locates the red plastic tab while the rear bolts
do most of the work of securing the gas tank.

Once the bolts are removed, lift the tank and gently
pull off the fuel tank overflow hose from the underneath
the right rear. Notice the bushings on the left
under my hand; these locate the bolts that hold the back
of the gas tank.

The '98 Tiger has a petcock on the left-hand side.
Remove the hose clamp with a pair of pliers and gently
pull off the fuel line. It's a good idea to have a
paper towel underneath because a few drops of fuel will
probably leak out of the hose after it's removed.

Which also reminds me -- it's a good idea to turn off
the petcock and run the bike until it stalls (i.e., the
fuel in the line is used up) to minimize the amount of
fuel that might spill when this line is removed.

Slowly and carefully lift the fuel tank off the bike,
but be careful that the petcock doesn't catch on the
side panels -- it could open up and spill fuel!
Use extreme caution whenever working on a fuel tank or
around gasoline.

Here's what the bike will look like after the plastic
gas tank is removed: